Metallic structures



O Umted States Patent 111135 3 [72] Inventors Dwight E. Peerman;Referencescited Leonard R. Vertnik, Minneapolis; Edgar R. UNITED STATESPATENTS RozimMinnmm'Minn' 2,919,255 12/1959 11m 260/23 1 pp 551,9802,994,456 8/1961 Peerman 220/81 [221 Filed M1015. 3,249,629 5/1966Rogier 260/4045 1 1 Patented Dec-2941970 3,357,935 12/1967 Fuhmeretal260/18 1 Assign Genmmmsim- 3,396,180 8/1968 Floydetal. 260/4045 W3,397,816 8/1968 12556161..." 220/81 3,398,164 8/1968 Rogier 260/4045 54METALLIC STRUCTURES 214, 227, Polyamide Digest; 156/217, 218, 331, 332;220/75, 76, 81; 260/18N, 404.5, 23

Primary Examiner-Robert F. Burnett Assistant Examiner-William A. PowellAttorneys-Anthony A. Juettner, William C. Babcock and Patrick J. SpanABSTRACT: A metallic structure, particularly a metallic container orcan, having lap seams in contrast to conventional hooked seams. The lapseam is bonded with polymeric fat acid polyamides wherein the polymericfat acid has a dimeric fat acid content greater than 90 percent byweight and preferably greater than 95 percent by weight.

PATENTEUDEDZS 1am I 3.650.806

IN VENTORS DWIGHT E. PEERMAN LEONARD R. VERTNIK EDGAR R. ROGIER QA/WATTORNEY METALLIC STRUCTURES This invention relates to metallicstructures having lap seams and more particularly to metallic containershaving such seams, in which the lap seam is bonded with a certainpolyamide resin, more particularly a polymeric fat acid polyamidewherein said polymeric fat acid has a dimeric fat acid content greaterthan about 90 percent by weight and preferably greater than 95 percentby weight.

In the past, seams of metallic structure were bonded with metallicsolders. Various resins have been proposed for cementing the seams ofmetallic structures such as metallic containers or cans as a substitutefor the solder. For various reasons, such resinous adhesives or cementshave not been successful. One deficiency has been the poor adhesion tomany metal surfaces. ln general, it was necessary therefore to utilize ahooked seam wherein the cement was largely a crack filler. Anillustration of such a hooked seam can be found in FIG. 2 of U.S. Pat.No. 3,0l l,676. In such a seam, it was necessary that the cement have avery low viscosity in the rnolten stage so that the resinous cementcould flow and completely fill the crack. This, however, had adisadvantage in that at sterilization temperatures the cement wouldagain become molten and flow out of the seam. Accordingly, such resinouscements were unsuitable for structures such as cans where sterilizationis required. Thennosetting resins which were proposed to solve thisproblem were not feasible, however, because curing times were too longparticularly in the highly mechanized automatic devices used in makingmetallic containers which devices are mechanically timed and operate athigh rates of speed.

It has now been discovered that polymeric fat acid polyamides preparedfrom polymeric fat acids having a dimeric fat acid content greater than90 percent by weight, and preferably greater than 95 percent by weightcan be employed as a cement for metallic structures having lap seams.With a lap seam, the requirement for low viscosity in the melt stage iseliminated as the adhesive can be applied by extrusion directly to themetal stock. Accordingly, high melting or softening point polyamides canbe employed, the only requirement being that the polyamide melting orsoftening point be below the melting point of the metal to be adhered.Where the final metallic structure is required to be sterilized, as incontainers for food products, such as beer, dog foods or human foods,the melting point of the resin must be higher than the sterilizationtemperature, which requirement is met by the products of this invention.The polyamides employed in this invention as the adhesive, possesshigh-temperature resistance (loss of a little strength as the meltingpoint is approached), good adhesion to.

bare or coated metals and adhesion to black iron," aluminum, or tinplate. The good adhesion to black iron" or tinplate is important sincesteel is still less expensive than aluminum and is the material ofchoice for processed food cans. Adhesion to aluminum is important,however, since aluminum cannot conveniently be soldered. The resins aretough and resilient and the seams will not fail when the can issubjected to the ordinary handling in manufacture, sterilization,packing and shipping. Furthermore, the adhesive is resistant to thematerials packed in the can, is not affected by the food products, andis not toxic.

Referring to the drawing:

FIG. 1 shows a container having a body 11 and an end closure 12 and sideseam 4;

H0. 2 shows the side seam 14 in detail which is composed of metal layers16 with the adhesive 18 therebetween; and

FIG. 3 is the same as FIG. 2, showing another modification of the seamin which the metallic layers 16 are offset or crimped to provide a morecontinuous circumferential surface.

In the specific drawing, the layers 16 represent the two ends of acircular can body. In metallic structures other than containers or cans,the layers 16 may be flat sheets, plates, castings, or the like of thesame or dissimilar metals which are to be joined by a lap seam.

The metallic structures of this invention having lap seams bonded withthe polymeric fat acids described may be bare metal or enameled orcoated metals. Illustrative of the metals which may be bonded are steel,aluminum, tin plate, copper, bronze and the like. This invention hasparticular application in the metallic can field having lap seams. Inthe first step of fabrication of such a can, a strip of adhesive(preferably about one-fourth inch wide, about 0.003 inch thick, and aslong as the joint) is applied to one edge of the can body blank. Thecircular can body is then formed by overlapping one-fourth inch andbonding the second edge of the can body blank to the adhesive containingedge. The adhesive can be applied by extrusion directly onto the edge ofthe metal blank or can be applied to a heated blank thereby melting theresin. After overlapping of the second can edge to the adhesivecontaining edge, the structure is first flash heated followed by quickcooling to below the melting point of the resin thus providing an almostinstant bonded lap seam. Can ends may be applied in the standard doubleseam fashion or may also be applied in a lap seam fashion. With thewidth and thickness of adhesive strip described above, the totalappliedadhesive will be about 0.08 grams or less for a standard l2-ouncebeverage can. Under good manufacturing practice, possible exposure ofthe adhesive in the side seam to the contents of the can will be limitedto a hair line about 0.002 inches thickness running the height of thecan. For a standard l2-ounce can, the total exposure of resin will thenbe about 0.01 square inch or less. If this exposure to the productcannot be tolerated, it may be desirable optionally to internally coatthe can in the conventional manner with an inert coating such as a vinylcoating after the container is formed.

While application of the resin by extrusion technique is the preferredmethod, the resin adhesive may be applied by a hot melt technique, byuse of a sheet or film, by solvent solution or by powder or granuleform.

As indicated, the resin adhesive employed in the present invention forbonding lap seams is a polymeric fat acid polyamide prepared frompolymeric fat acids having a dimeric fat acid content greater thanpercent by weight and preferably greater than percent by weight. Thesepolyamide resins are prepared by conventional amidification processeswhich are well known. In general, in such amidification reaction thepolyamide forming reactants are preferably heated to a temperaturebetween and 300 C. and the water of reaction is removed.

The polymeric fat acids are well known. A summary of the preparationthereof is foundin U.S. Pat. No. 3,157,681. Com mercially availablepolymeric fat acids so prepared from tall oil fatty acids generally havea composition as follows:

By weight;

percent C 8 monobasic acids (monomer) 5-15 C3 dibasic acids (dimer)60-80 C and higher polybasic acids (trimer) 10-35 The relative ratios ofmonomer, dimer and trimer in such unfractionated polymeric fat acids aredependent on the nature of the starting material and the conditions ofpolymerization. For the purposes of this invention, the term monomericfat acids" refers to the unpolymerized monomeric acids, the term"dimeric fat acids" refers to the dimeric fat acids, and the tentrimeric fat acids" refers to the residual higher polymeric formsconsisting primarily of trimer acids but containing some higherpolymeric forms. The term polymeric fat acids" as used herein isintended to be generic to polymerized acids obtained from fat acids" andconsists of a mixture of monomeric, dimeric and trimeric fat acids. Theterm fat acids is intended to include saturated, ethylenicallyunsaturated and acetylenically unsaturated, naturally occurring andsynthetic monocarboxylic aliphatic acids containing from 8 to 24 carbonatoms. l

The saturated fat acids are generally polymerized by somewhat differenttechniques than those described in U.S. Pat. No. 3,157,681, but becauseof the functional similarity of the polymerization products, they areconsidered equivalent to those prepared by the methods described asapplicable to the ethylenically and acetylenically unsaturated fatacids. While saturated acids are difficult to polymerize, polymerizationcan be obtained at elevated temperatures with a peroxidic catalyst suchas di-t-butyl peroxide. Because of the generally low yields of polymericproducts, these materials are not currently commercially significant.Suitable saturated fat acids include branched and straight chain acidssuch as caprylic acid, pelargonic acid, capric acid, lauric acid,myristic acid, palmitic acid, isopalmitic, stearic acid, arachidic acid,behenic acid and lignoceric acid.

The ethylenically and acetylenically unsaturated fat acids which may bepolymerized and their method of polymerization are described in theabove mentioned U.S. Pat. No. 3,157,681.

Reference has been made hereinabove to the monomeric, dimeric andtrimeric fat acids present in the polymeric fat acids. The amounts ofmonomeric fat acids, often referred to as monomer, dimeric fat acids,often referred to as dimer, and trimeric or higher polymeric fat acids,often referred to as trimer, present in polymeric fat acids may bedetermined by conventional gas-liquid chromatography of thecorresponding methyl esters. Another method of determination is amicromolecular distillation analytical method. This method is that of R.F. Paschke et a1., .1. Am. Oil Chem. Soc., XXXI (No. 1 5, 1954), whereinthe distillation is carried out under high vacuum (below 5 microns) andthe monomeric fraction is calculated from the weight of productdistilling at 155 C., the dimeric fraction calculated from thatdistilling between 155 C. and 250 C., and the trimeric (or higher)fraction is calculated based on the residue. Unless otherwise indicatedherein, this analytical method was that employed in the analysis of thepolymeric fat acids employed in this invention. When the gasliquidchromatography technique is employed, a portion intermediate betweenmonomeric fat acids and dimeric fat acids is seen, and is termed hereinmerely as intermediate," since the exact nature thereof is not fullyknown. For this reason, the dimeric fat acid value determined by thismethod is slightly lower than the value determined by the micromoleculardistillation method. Generally, the monomeric fat acid contentdetermined by the micromolecular distillation method will be somewhathigher than that of the chromatography method. Because of the differenceof the two methods, there will be some variation in the values of thecontents of various fat acid fractions. Unfortunately, there is no knownsimple direct mathematical relationship correlating the value of onetechnique with the other.

As earlier indicated, the polymeric fat acids employed to prepare thepolyamides used in this invention have a dimeric fat acid content inexcess of 90 percent by weight and preferably in excess of 95 percent byweight. Such polymeric fat acids are obtained by fractionation bysuitable means such as high vacuum distillation or by solvent extractiontechniques from polymeric fat acids having lower dimeric fat acidcontents, such as the common commercially available products describedearlier.

With polymeric fat acids having the dimeric fat acid content in excessof 90 percent, the polyamide products therefrom will desirably havenumber average molecular weights in excess of 10,000 and preferably inthe range of 15,00025,000.

The polyamides are prepared by reacting the polymeric fat acids with adiamine. The resins may also include other copolymerizing acid and aminecomponents and the diamine employed may be a single diamine or a mixtureof two different diamines. In addition, small amounts of monomeric,monocarboxylic acids may be present. With regard to any of the acidcomponents, any of the equivalent amide-forming derivatives thereof maybe employed, such as the alkyl and aryl esters, preferably alkyl estershaving from 1 to 8 carbon atoms, the anhydrides or the chlorides.

The diamines employed may be aliphatic, cycloaliphatic or aromaticdiprimary diamines, which may be ideally represented by the formulawhere R is an aliphatic, cycloaliphatic or aromatic radical preferablyhaving from 2 to about 40 carbon atoms. While R is preferably ahydrocarbon radical, R may contain ether linkages such as in diaminesprepared from diphenyl ether sometimes called diphenyl oxide. R may alsobe saturated or unsaturated, straight or branched chain. Representativeof such diamines are the alkylene diamines having from 2 to 20 carbonatoms (preferably 2-6) such as ethylene diamine, 1,2- diamino propane,1,3-diamino propane, 1,3-diamino butane, tetramethylene diamine,pentamethylene diamine, hexamethylene diamine, decamethylene diamine,and octadecamethylene diamine; metaxylylene diamine, paraxylylenediamine, cyclohexylene diamine, bis(fl-aminoethyl) benzene,cyclohexane-bis( methyl amine), diaminodicyclohexylmethane, methylenedianiline, bis(aminoethyl)diphenyl oxide, and dimeric fat diamine. Thediamine may be employed alone or mixtures of two or more may beemployed. The most preferred diamines are the alkylene diamines in whichthe alkylene group has from 4-6 carbon atoms and mixtures thereof withdimeric fat diamine (preferably having 36 carbon atoms).

The dimeric fat diamine, sometimes referred to as dimer diamine,"dimeric fat amine, or polymeric fat acid diamine" are the diaminesprepared by amination of dimeric fat acids. Reference is made thereto inU.S. Pat. No. 3,010,782. As indicated therein, these are prepared byreacting polymeric fat acids with ammonia to produce the correspondingnitriles and subsequently hydrogenating the nitriles to thecorresponding amines. Upon distillation, the dimeric fat diamine isprovided which has essentially the same structure as a dimeric fat acidexcept that the carboxyl groups are replaced by -C H,NH, groups.Further, this diamine is also described in Research and DevelopmentProducts Bulletin, CDS 2-63 by General Mills, lnc., June 1, 1963, asDimer Diamine" illustrated by the formula H I 1 l D-NH where D is a36-carbon hydrocarbon radical of the dimeric fat acid.

The copolymen'zing compounds commonly employed are aliphatic,cycloaliphatic or aromatic dicarboxylic acids or esters which may bedefined ideally by the formulae:

mow-coon, and R1OOCRCOOR1 where R is an aliphatic, cycloaliphatic oraromatic hydrocarbon radical preferably having from 1 to 20 carbon atoms(the most preferred being where R is an alkylene radical having from6-12 carbon atoms) and R, is hydrogen or an alkyl group (preferablyhaving from 1 to 8 carbon atoms). lllustrative of such acids are oxalic,malonic, adipic, sebacic, suberic, pimelic, azelaic, succinic, glutaric,isophthalic, terephthalic phthalic acids, benzenediacetic acid,naphthalene dicarboxylic acids and 1,4- or 1,3-cyclohexane dicarboxylicacid.

Essentially molar equivalent amounts of carboxyl and amine groups areemployed in preparing the polyamide. Where copolymerizing dicarboxylicacids are employed, it is preferred that the carboxyl groups from thepolymeric fat acid EXAMPLE 1 A polyamide was prepared in which thereactants and amounts were as follows:

lbs. Sebacic acid 16. 3 Hexamethylene diamine 22. 4

Polymeric fat acids (polymerized tall oil fatty acids) The analysis ofthe polymeric fat acids is as follows in which the amount of monomer,intermediate, dimer and trimer were determined by gas-liquidchromatography (GLC).

Percent monomer (M) 0. 9 Percent intermediate (1) 1. 9 Percent dimer (D)96. 6 Percent trimer (T) 0. 6 Neutralization equiv. (N.E.) 292Saponification equiv. (S.E.) 285 The above reactants were charged into areactor and heated to 250 C. over a period of about 4 hours. At thispoint vacuum was applied for about 2 hours at 250 C. and for about Ihour at 270 C. Analysis of the resulting product was as follows:

In the same manner as example I, a polyamide was prepared from the samepolymeric fat acids, the reactants and amounts being asfollows:

Acid (meq./kg.)

29. Amine (meq./kg.) 18.5 Ball & Ring Softening Point, C 200 InherentViscosity 0. 64 Tensile Ultimate (p.s.i 5, 800 Yield Strength (p.s.i 4,230 Elongation (percent) 206 EXAMPLE 3 In the same manner as example 1,a polyamide was prepared from hexamethylene diamine and polymeric fatacids (polymerized tall oil fatty acids). The reactants, amounts andanalysis of the resulting product were as follows:

Hexamethylene diamine lbs. 30 Polymeric fat acids "lbs--- 133 Analysis(polymeric fat acids):

Percent M 0. 1 Percent I 3. 2 Percent D 96.2 Percent T 0. 5 NE 292 SE287 Product Analysis:

Acid (meq./kg.) 13. 0 Amine (meq., kg.) 8. 5 Inherent Viscosity 0. 6Ball and Ring Softening Point, C 140 Yield Strength (p.s.i.) 1,225Tensile Ultimate (p.s.i 4, 805 Elongation (percent) 515 EXAMPLE 4 In thesame manner as example I, a polyamide was prepared from hexamethylenediamine, suberic acid and polymeric fat acids (polymerized talloilfattyacids). The reactants, amounts thereof, and analysis of the resultingproduct were as follows:

Hexamethylene diamine lbs 45. 8 Suberic Acid -lbs- 28. 5 Polymeric fatacids -lbs- Analysis:

Percent M 1. 7 Percent I 2. 1 Percent D 95. 0 Percent T 1. 2 NE 294 SE287 Product Analysis:

Acid (meq./kg.) 78. 9 Amine (meq./kg.) 6. 9 Inherent Viscosity 0. 57Ball & Ring Softening Point C.) 189 Tensile Ultimate (p.s.i.) 5, 170Yield Strength (p.s.i.) 2, 415

Elongation (percent) s EXAMPLE 5 In the same manner as example 1. apolyamide was prepared from hexamethylene diamine, sebacic acid and thepolymeric fat acids of example 4. The reactant amounts and analysis ofthe resulting product were as follows:

Polymeric fat acids grams 2, 650 Sebacic Acid -do- 2, Hexamethylenediamine do 1, 840

Product Analysis:

EXAMPLE 6 In the same manner as example 1, a polyamide was prepared from4,4-diamino-3,3'-dimethyldicyclohexylmethane and the polymeric fat acidsof example 3. The reactant amounts and analysis of the resulting productwere as follows:

Polymeric fat acids -lbs- 1254,4-diamino-3,3-dimethyldicyclohexylmethane -lbs- 52 Product Analysis:

Acid (meq./kg.-) 15. 9 Amine (meq./kg.) 16. 0 Inherent Viscosity 0. 6 LTensile Ultimate (p.s.i 5, 570 Yield Strength (p.s.i 4, 355 Elongation(percent) 230 EXAMPLE 7 In the manner as example 1 and employing thepolymeric fat acids of example 1, a polyamide was prepared from 1,4-bis(/3-aminoethyl)benzene. The reactant amounts and analysis of theresulting product were as follows:

Polymeric fat acids grams 3, 656 1,4-bis'(fi-aminoethyl) benzene -do- 1,053 Product Analysis:

Acid (meq.,/kg.) 10. 9 Amine (meq./kg.) 23. 6 Ball and Ring SofteningPoint (/C.) 17 0 Inherent Viscosity 0. 71 Tensile Strength (p.s.i 4, 910Yield Strength (p.s.i 2, 645 Elongation (percent) 440 EXAMPLE 8 In thesame manner as example i, employing the polymeric fat acids of exampleI, a polyamide was prepared from hex- EXAMPLE 10 An evaluation was madeon the polyamides for tensile shear and button tensile properties oncold rolled steel and 2024-T3 amethylene diamine. The reactant amountsand analysis of the 5 aluminum alloy. The tensile button samples weremolded at resulting product were as follo various temperatures. Theoptimum temperature was 500 F. Polymeric fat acids lbs 75 for steel and550 F. for aluminum. For comparison purposes, Hexamethvlene h 94 testswere also run on Surlyn A and Zytel 69. The tensile shear product A'specimens were prepared at approximately the polyamide ex- Acid(meq./kg.) 35. 5 1O trusion temperatures for the aluminum test specimensand at Amine (meg/kg.) 14- 50 F. higher for the steel specimens. Themetals were etched ggiff; f g 5 according to Procedure A (dichromateetch) for aluminum al- Tensile Strength (p si 3 610 loys and ProcedureA4 (hydrochloric acid etch) for carbon Yield Strength (psi) I 065 steelas described in the June, 1961, proposals of the Elongation (percent)555 ASTM-D 1 4, 51119 X1 Committee On Adhesives Testing. Table II belowsummarizes the results of these tests.

EXAMPLE 9 The tensile shear strength (p.s.i. at 24 C. was determined oncan stock in accordance with ASTM D 1002-64. The results are as follows:

TABLE I 0 mm Tensile shear strength (p.s.i.)

11m onding 6086 Aluminum 5052-H 19 Aluminum tenzperstock (0.017) stock(0.008) 'Iinplate stock (0.007)

ure, 8 C. Coated Uncoated Coated Uncoated Coated Uncoated Polyamide Ex.1 230 2, 848 2,184 1,320 MF 2,219 MF 2, 592 135 Ex. 4 240 2,388 2, 2231,323 MF 2,280 MF 2, 472 2,176 Ex. 5 235 2, 852 1,168 1,374 MF 1,1152,872 224 Ex. 6 230 2,325 1, 665 1,417 MF 1,367 MF 2,6278% MF 1 786 Ex.7 240 2,595 1, 955 1,333 MF 1,462 MF 2, 71s 2, 250 EX. 8 230 2,172 1,884 1,352% MF 1, 241 1, 994 1, 144

Nora: All number values are mans rather than bond failure,

of 5 which failed in the metal, not in the bond.

TABLE I? Tensile shear, p.s.i. Button tensile, p.s.i.

Steal Aluminum Stea Aluminum Button Test Avg. Avg. Avg. Avg. bondingAvg. Avg. Avg. Avg. temp, of of 01 of temp, of of of of Product ofExample /F. 5 3 5 3 /F. 3 2 3 2 16 11111 film l, 987 2, 075 2, 562 2,612 500 2, 667 2, 938 1, 783 1, 825 75 550 2, 533 2 700 2,033 2,050 170498 574 935 1,003 500 1, 328 1 363 170 550 1,228 1,248

2-4 mil film 75 1, 758 1, 929 1, 772 2, 024 500 2, 758 2, 975 1, 817 2,038 75 550 2, 500 2, 725 2, 447 2, 535 675 727 1, 016 1, 176 500 1, 9452, 080 550 1, 745 1, 798

3-4 mil film 75 l, 217 1, 278 l, 679 1, 738 500 2, 542 2, 688 1, 725 1,82 75 550 2, 503 2, 530 2, 073 2, 170 17 22 29 33 500 305 310 170 550328 348 4-5 mil film 75 1, 977 2, 047 2, 620 2, 666 500 2, 642 3, 163 1,758 1, 833 7g 550 2,300 2,325 2 225 110 ii'iai ibb ifii 170 Burlyn A45mil 75 1, 090 1, 154 1, 778 1,859 500 3,100 a, 275 75 550 2, 833 2, 9252, 850 2, 962 170 260 282 657 716 500 677 835 170 550 1 852 862 Zytei69''7 mil film. 75 374 390 500 75 550 750 835 1, 400 1, 525 75 600 3,483 3, 775 170 500 310 325 170 204 234 550 525 550 510 540 170 1 600 1,145

1 Poor Bond. 1 Bond shows poor adhesion, too weak to test. 1 No Bond. 1Not Run Adhesive thickness, 2% mils.

"For GM] polymers, 450 F. gave very 'Very severe oxidation occurs at 550F. and higher.

"'"Polymor forms poor adhesive bonds, particularly in tensile shear.

low values, less than 1,000 p.s.i., poor bonds.

EXAM PLE ll Using a resin of the same reactants as in example 1, theeffect of overlap dimensions was studied. On 0.064 inch 2024-T-3aluminum, the results were as follows:

Tensile shear,

Overla dimension in. p.s.i.: M 2, 892

To compare specimens overlapped one-eighth inch, it was necessary to usethin can makers uncoated tinplate. With this substrate, the 15-inchspecimens gave a tensile shear value of 2,702 psi. as compared to 2,435p.s.i. obtained with a /4-inch overlapped specimen. Tinplate specimensoverlapped onehalf, three-fourths, and one inch were also tested. Theseall failed in the metal rather than in the adhesive bond.

EXAMPLE [2 The effect of polymer viscosity on tensile strength of thesame polyamide of example 11 was studied. The relative viscosities wereobserved by Brabender Readings at 200 C. The bond temperature was 230 C.the bond thickness was 5 mils, and the crosshead speed was 0.2 inch/min.The specimens were 5086 Aluminum 0.017 inch thick. The overlap dimensionwas one-fourth inch. The results are as follows:

This indicates that the medium viscosity range is desirable for adhesiveuse.

EXAMPLE 13 The peel strengths of various polymers were determinedincluding for comparison two commercially available nylon resins. Theresults are as indicated.

Bond Peel tempstrength erature, mean, Polymer lbs./in

A. Polymer of hydrogenated and distilled polymerized tall oil fattyacids, suberic acid and hexamethylene diamine B. Polymer of hydrogenatedand distilled polymerized tall oil fatty acids, sebacic acid andhexamethylene diamine (75/25) C. Polymer of hydrogenated and distilledpolymerized tall oil fatty acids, sebacic acid and hexamethylene diamine(50/50) 50/50 D. Polymer of hydrogenated and distilled polymerized tailoil fatty acids and 4,4'-diamino-3,3'-dimethyldicyclohexylmethane E.Polymer of hydrogenated distilled polymerized tall oil fatty acids andl,4-bis(B-amin0ethyl)-benzene F. Polymer of hydrogenated and distilledpolymerized tall oil fatty acids and 4,4'-diaminodicyclohexylmethane G.Polymer of hydrogenated and distilled polymerized tall oil fatty acidsand 4,4-bis(B-aminoethyl)-diphenyl oxide.

in the foregoing polymers the molar equivalent amounts have beenindicated for the copolymer where copolymerizing acids were employed inthe form of a ratio showing the molar ratio of each type of polymer, thefirst FIG. being the amount of polymer of the polymerized tall oil fattyacids.

While various modifications of the invention have been described, it isto be understood that other variations are possible without departingfrom the spirit of the invention as defined in the following claims.

We claim:

1. A metallic structure having lap seams, said lap seams being bonded byan adhesive consisting essentially of a polymeric fat acid polyamidewherein said polymeric fat acid has a dimeric fat acid content greaterthan about percent by weight and is a polymerized monocarboxylic fattyacid, said monocarboxylic fatty acid having from 8 to 24 carbon atoms,said polyamide consisting of the amidification product of substantiallymolar equivalent amounts of amine and'carboxyl groups selected from thegroups consisting of: v r

A. said polymeric fat acid and a diamine selected from the groupconsisting of:

a. hexamethylene diamine; b..xylylenediamine;

c. cyclohexylene diamine;

d. bis(B-amin0ethyl) benzene;

e. cyclohexanebis(methylamine);

f. diaminodicyclohexylmethane;

g. methylene dianiline;

h. bis(B-aminoethyl)diphenyloxide;

i. the diamine of polymerized monocarboxylic fatty acids, saidmonocarboxylic acids having from 8 to 24 carbon' atoms; and B.copolymers thereof with up to 50 equivalent percentof a dicarboxylicacid of the formula where R is an alkylene radical having from 6 to 12carbon atoms.

2. A metallic structure as defined in claim 1 wherein said polymeric fatacid has a dimeric fat acid content greater than percent by weight.

3. A metallic structure as defined in claim 1 wherein said metallicstructure is a metallic container.

4. A metallic structure as defined in claim 1 wherein said polymeric fatacid is polymerizedtall oil fatty acids.

5. A metallic structure as defined in claim 4 in which said diamine ishexamethylene diamine and said dicarboxylic acid is sebacic acid.

6. A metallic structure as defined in claim 4 in which said diamine ishexamethylene diamine and said dicarboxylic acid is suberic acid.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent'No. 3 55 6Dated March 12, 1971 Inventor(s) Dwight E. Peerman, Leonard R. Vertnik8c Edgar R. Rog

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Col 1, line 6H, the numeral 4" should read -1 Col. 1, line 13, "the"should read --a---. C01. 5, line 31, after "follows:" insert -Polymericfat acids 5000 grax l, -diamino3, 3' dimethyldicyclohexylmethane 2095gral The analysis of the resulting product was as follows:-- Col 6, line57, after "the" insert -same Col. 7, Table I, under column entitled"5o52-H19...Unooeted lines 1 and 2, the numeral "2, 219W" should read--l, 219 ME and the numeral "2, 280 ME" should read --1, 280 m. TableII, under column entitled "Button tensile .St Avg. of 2," the fifth linefrom the bottom, the nume "835" should read 825- Col. 10, line 6, thesecond "50/50" should be deletedline &9, insert the formula HOOC-R' CO0HSigned and sealed this 29th day of June 1971 (SEAL) Attest:

WILLIAM E SCHUYL Commissioner of I EDWARD M .FLE TCHER JR AttostingOfficer

